1. Field of the Invention
The present invention relates to a hollow golf club head which has a face plate attached on the front face of the head body and is made of lightweight metal such as a titanium alloy.
2. Description of the Related Art
To obtain high resilience at the face of the golf club head, conventional golf club heads of the driver or wood type have been disclosed which increase the face plate area size in conjunction with increasing the overall volume of the golf club head. Some of the proposed golf club heads have an overall volume of more than 400 cc.
However, increasing both the area of the face plate and the overall volume of the club head leads accordingly to an increase of the face weight. Therefore, a technique has been proposed which decreases the thickness of the face plate while keeping the increase of the face plate weight as little as possible.
However, by uniformly decreasing the thickness of the overall face plate, a sufficient thickness at the sweet spot which frequently strikes a golf ball cannot be maintained, thus resulting in breakage at the spot and failure in to impart high resilience to the ball.
In view of the above problems, as disclosed in Japanese Patent Laid-Open (Kokai) Publication No. 9-192273, golf club head has been proposed which attains an improved resilience by forming the central portion of the face plate to be thick, and forming the perimeter thereof to be thin.
However, this conventional golf club head may show good performance when a ball is hit at the central thick portion of the face plate, but has problems when a golf ball is hit off center. For example, when a ball is hit at the boundary between the thick and thin portions, ball flight deviation occurs, and when a ball is hit at the thin portion, significant distance loss occurs. Moreover, the above-described conventional golf club head has a problem in that repeated use tends to result in cracking at the boundary part between the thick and thin portions.
The present invention has been made in view of the above problems, and its object is to provide a golf club head having a face plate of high strength and high resilience and having an excellent directional stability of the ball trajectory.